Add the ProxyPassReverse directive which allows Apache to be

used as a full-featured Reverse Proxy in front of a backend
webserver cluster.

Submitted by: Ralf S. Engelschall
Reviewed by: Martin Kraemer, Ralf S. Engelschall


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@80296 13f79535-47bb-0310-9956-ffa450edef68